Regular Expressions 101

^start of line

Positive Lookahead(?=(?:\D*\d){10}(?:(?:\D*\d){3})?$)

Non-Capturing Group(?:\D*\d){10}

{10}repeats the group contents below exactly 10 times:

\D*any character that's not a digit, repeated any number of times

\da digit

Non-Capturing Group(?:(?:\D*\d){3})?

?repeats the group contents below at most once:

Non-Capturing Group(?:\D*\d){3}

{3}repeats the group contents below exactly 3 times:

\D*any character that's not a digit, repeated any number of times

\da digit

$end of line

Character Class[\d-]+

+matches at least one character from the set below:

\da digit

-the literal - (45₁₀ / 55₈ / 2D₁₆)

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

25 tokens

Regular Expression

^(?=(?:\D*\d){10}(?:(?:\D*\d){3})?$)[\d-]+$

New

978-1-56619-909-4 2
978-1-56619-909-4
1-56619-909-3 
1-56619-909-3
isbn446877428ydh
55 65465 4513574
1257561035
1248752418865

978-1-56619-909-4 2
978-1-56619-909-4
1-56619-909-3 
1-56619-909-3
isbn446877428ydh
55 65465 4513574
1257561035
1248752418865